I went through the same thing when I was 15. I was having a tough time at home, always fighting with my Mom and I had just broken up with my first boyfriend. I felt like my life was spinning out of control, and food was one of the only things that I could control (I didn't realize that until a few years later).

I never thought that I was overweight, but I was just never hungry. Also, the less I ate the less I needed, it was like my stomach shrunk and couldn't hold a lot of food. I remember I ate 1 1/2 chicken nuggets and was so full, I felt like I had just eaten a huge meal.

I don't remember how I snapped out of it, my parents were really worried and would punish me if I didn't eat enough, which just made me more upset. Maybe talk to your daughter and see if it could be a similar situation to mine. I am sorry that I can't be of more help, I can only share my story. I am now healthy and eat normally.